The invention, generally, is a simplified circuit for mixing two logarithms under the control of two numbers. More particularly, a logarithm mixer circuit in accordance with the invention is in a form of conversion circuit for mixing digital representations of logarithm values.
Instead of the usual mathematical process of determining antilogs, summing them, and then, determining the log again, a log mixer circuit that is constructed and arranged according to the principles of the present invention utilizes the much simpler mathematical processes involving adding, subtracting, and using a look-up table.
In the patented prior art, there is a U.S. Pat. No. 4,290,111 to Dillon which is assigned to the same Assignee as the present invention. While that prior patent teaches the determination of a difference value between two signals that represent respective input measurements and uses a logarithmic conversion circuit to provide a signal with a predetermined representative value, the respective component parts are interconnected to achieve results that are completely different from those provided by the circuit of the present invention.
Although the present invention utilizes some of the basic circuit component parts as in the Dillon circuit, the overall arrangement of the present invention, as well as the objectives of the invention, are totally different. These and other distinctions will become more apparent as the description proceeds.